Loot tables are not working when integrated into a datapack.
Steps :
/datapack enable "file/datapack" first/summon stray ~ ~ ~{DeathLootTable:"test:folder/table1"}
Then the mob drops nothing, even if weight is set to 1000.
Maybe the function set_nbt is no longer supported in 1.13 snapshots.
Here is the file so you can experiment that problem.
I can already tell you 2 things:
weight is irrelevant.
~the loot table fails to load/errors, Iām trying to find out why though.~
EDIT: the loot table works for me, actually.